Switching components and memory units

ABSTRACT

Some embodiments include a switching component which includes a selector region between a pair of electrodes. The selector region contains silicon doped with one or more of nitrogen, oxygen, germanium and carbon. Some embodiments include a memory unit which includes a memory cell and a select device electrically coupled to the memory cell. The select device has a selector region between a pair of electrodes. The selector region contains semiconductor doped with one or more of nitrogen, oxygen, germanium and carbon. The select device has current versus voltage characteristics which include snap-back voltage behavior.

RELATED PATENT DATA

This patent resulted from a divisional of U.S. patent application Ser.No. 14/184,400, which was filed Feb. 19, 2014, and which is herebyincorporated herein by reference.

TECHNICAL FIELD

Switching components and memory units.

BACKGROUND

Memory is one type of integrated circuitry, and is used in systems forstoring data. Memory is usually fabricated in one or more arrays ofindividual memory cells. The memory cells are configured to retain orstore information in at least two different selectable states. In abinary system, the states are considered as either a “0” or a “1”. Inother systems, at least some individual memory cells may be configuredto store more than two levels or states of information.

Integrated circuit fabrication continues to strive to produce smallerand denser integrated circuits. Accordingly, there has been substantialinterest in memory cells that can be utilized in structures havingprogrammable material between a pair of electrodes; where theprogrammable material has two or more selectable resistive states toenable storing of information. Examples of such memory cells areresistive RAM (RRAM) cells, phase change RAM (PCRAM) cells, andprogrammable metallization cells (PMCs)—which may be alternativelyreferred to as a conductive bridging RAM (CBRAM) cells, nanobridgememory cells, or electrolyte memory cells. The memory cell types are notmutually exclusive. For example, RRAM may be considered to encompassPCRAM and PMCs. Additional example memory includes ferroelectric memory,magnetic RAM (MRAM) and spin-torque RAM.

Programmable memory cells of the types described above may be highlyscalable and thus suitable for utilization in future generations ofmemory. However, problems are encountered in attempting to utilize suchmemory cells. For instance, the memory cells may be “leaky”; andaccordingly may be paired with select devices in order to better controlcurrent flow to and from the memory cells.

An example prior art memory array 1 is shown in FIG. 1. The memory array1 comprises a plurality of memory units 2, each including a memory cell3 and a select device 4. The memory cells 2 are interposed atcross-points between rows 6 (also called wordlines or access lines) andcolumns 5 (also called bitlines or sense lines). In each memory unit 2,the memory cell 3 has a first terminal connected to a wordline 6 and asecond terminal connected to a select device 4. The select device 4 hasa second terminal connected to a bitline 5.

The select devices may be considered to be switchable components (orswitching components), in that they may switch a circuit from an “open”configuration to a “closed” configuration. Individual memory cells maybe selected by closing an adjacent switching component while creating avoltage differential between a wordline and a bitline.

It is desired to develop improved switching components, and in someaspects to develop improved switching components suitable forutilization as select devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an example prior art memory array.

FIG. 2 graphically illustrates a relationship between current (I) andvoltage (V) for an example embodiment component having snap-backcharacteristics; and FIG. 2A shows an expanded region from the graph ofFIG. 2.

FIG. 3 diagrammatically illustrates an example embodiment switchingcomponent incorporated into a memory unit.

FIG. 4 diagrammatically illustrates another example embodiment switchingcomponent incorporated into a memory unit.

FIG. 5 diagrammatically illustrates another example embodiment switchingcomponent incorporated into a memory unit.

FIGS. 6A-E diagrammatically illustrate a series of example embodimentswitching components.

FIGS. 7A-E diagrammatically illustrate another series of exampleembodiment switching components.

FIGS. 8A-E diagrammatically illustrate another series of exampleembodiment switching components.

FIGS. 9A-E diagrammatically illustrate another series of exampleembodiment switching components.

FIGS. 10A-E diagrammatically illustrate another series of exampleembodiment switching components.

FIGS. 11A and B diagrammatically illustrate another series of exampleembodiment switching components.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Some embodiments include switching components which comprisesemiconductor material between a pair of electrodes. The semiconductormaterial may be, for example, silicon; and in some embodiments may bedoped with one or more of nitrogen, oxygen, germanium and carbon. Anadvantage of the switching components described herein is that such mayhave current versus voltage characteristics which include snap-backvoltage behavior.

FIG. 2 graphically illustrates current (I) versus voltage (V) of anexample embodiment device exhibiting snap-back voltage behavior.Specifically, positive current flow through the device increases withincreasing positive voltage along a first path 10 until sufficientvoltage is achieved to jump the device to a second path 12. Theillustrated device is symmetric, so that paths 10 and 12 alsointerchange with one another utilizing negative voltage and negativecurrent flow. Snap-back voltage regimes are diagrammatically illustratedwith double-headed arrows 14.

The voltage at which the device of FIG. 2 transitions from path 12 backto path 10 may be different than that where the device transitions frompath 10 to path 12, as shown in FIG. 2A. Specifically, FIG. 2A utilizesa dashed-line trail 15 to diagrammatically illustrate current versusvoltage behavior of the example device. The trail comprises a region 16along the first path 10, and then jumps to the second path 12 at athreshold voltage 17. Subsequently, the trail follows the second path 12downwardly during decrease in voltage until a holding voltage 18 isreached whereupon the trail jumps back to the first path. A snap-backvoltage may be defined as a voltage difference between the holdingvoltage 18 and the threshold voltage 17.

Switching components exhibiting the snap-back behavior of FIGS. 2 and 2Amay be advantageous for utilization as select devices in memory units.Specifically, the switching components may exhibit behavior such that aselected memory cell will have much higher current flow then adjacentnon-selected memory cells, which may improve access times and/or improvereliability relative to conventional systems.

Some example embodiment switching components are described withreference to FIGS. 3-11.

Referring to FIG. 3, a region of a memory array 20 is shown to comprisea switching component 22 electrically coupled to a bitline 5 and amemory cell 3. The switching component is thus configured forutilization as a select device 4 of the type described above withreference to FIG. 1.

Switching component 22 comprises a pair of electrodes 30 and 32, and aselector region 34 between the electrodes.

The electrodes 30 and 32 may be referred to as a first electrode and asecond electrode, respectively. The electrodes 30 and 32 compriseelectrode compositions 31 and 33, respectively. Such electrodecompositions may be the same as one another, or may be different thanone another.

In some embodiments, one or both of the electrodes may comprise, consistessentially of, or consist of carbon; either alone or in combinationwith nitrogen. If nitrogen is present, it may be present to less than orequal to about 75 atomic percent.

In some embodiments, one or both of the electrodes may comprise one ormore of Ta, Ti and W, in combination with nitrogen. The nitrogen may bepresent to less than or equal to about 75 atomic percent. In someembodiments, one or both of the electrodes may comprise, consistessentially of, or consist of one or more of TaN, TiN and WN; incombination with one or more of O, C and Al. The formulas TaN, TiN andWN are utilized to indicate elemental components, rather than indicatingany particular stoichiometry.

The selector region 34 comprises selector material 35. Such materialincludes semiconductor, and in some embodiments may comprise, consistessentially of, or consist of silicon doped with one or more ofnitrogen, oxygen, germanium and carbon. In embodiments in which theselector material comprises silicon doped with nitrogen and/or oxygen, atotal concentration of dopant may be within a range of from greater thanzero atomic percent to about 10 atomic percent. In embodiments in whichthe selector material comprises silicon doped with one or both of carbonand germanium, the dopant may be present to a total concentration withina range of from greater than zero atomic percent to about 50 atomicpercent (and in some embodiments may be present within a range of fromgreater than about one atomic percent to about 50 atomic percent).

The selector material 35 comprises a thickness “T”; which in someembodiments may be within a range of from about 20 Å to about 350 Å. Itcan be desired that the material 35 be kept relatively thin, providedenough of the material is present for desired switching characteristics.The switching component 22 may have better scalability for higher levelsof integration if the device is kept compact; and further the switchingcomponent may have better durability (for instance, less susceptibilityto tipping) if it is kept compact. In some embodiments, it is found thata relatively thin layer of doped silicon (for instance, silicon dopedwith nitrogen and/or with one or more of oxygen, carbon and germanium)can match performance characteristics of a thicker layer of undopedsilicon in the switching devices described herein.

In the shown embodiment, the selector region 34 comprises a singlehomogeneous selector material 35 that directly contacts each of theelectrodes 30 and 32. In other embodiments, (for instance, embodimentsdiscussed below with reference to FIGS. 4 and 5) the selector region maycomprise two or more different materials.

Some example switching components 22 having only a single homogeneousselector material 34 are shown in FIGS. 6A, 7A, 8A, 9A and 10A. Theelectrodes 30 and 32 shown in such embodiments may comprise any of theelectrode compositions described above. For instance, in some exampleembodiments, the electrodes may comprise, consist essentially of, orconsist of carbon.

Referring to FIG. 4, a region of a memory array 20 a is shown tocomprise a switching component 22 a electrically coupled to the bitline5 and the memory cell 3. The switching component is thus configured forutilization as a select device 4 of the type described above withreference to FIG. 1.

Switching component 22 a comprises electrodes 30 and 32, and comprises aselector region 34 a between the electrodes.

The electrodes 30 and 32 may comprise the same electrode compositionsdiscussed above with reference to FIG. 3.

The selector region 34 a comprises alternating materials 40 and 42. Insome embodiments, the materials 40 and 42 may be referred to as firstand second materials, respectively. At least one of the materialscomprises semiconductor, and such material may comprise any of thecompositions discussed above regarding material 35 of FIG. 3.

Some example embodiments of switching components 22 a having selectorregions 34 a with alternating first and second materials 40 and 42 areshown in FIGS. 6B, 6C, 7B, 7C, 8B, 8C, 9B, 9C, 10B and 10C.

The embodiments of FIGS. 6B and 6C show that in some embodiments one ofmaterials 40 and 42 may consist of, or consist essentially of silicon;while the other comprises silicon doped with nitrogen. The silicon maybe directly against the electrodes in some embodiments, and the silicondoped with nitrogen may be directly against the electrodes in otherembodiments. In some embodiments, the silicon doped with nitrogen maycomprise nitrogen to a concentration within a range of from greater thanzero atomic percent to less than or equal to about 10 atomic percent.

The embodiments of FIGS. 7B and 7C show that in some embodiments one ofmaterials 40 and 42 may consist of, or consist essentially of silicon;while the other comprises silicon doped with oxygen. The silicon may bedirectly against the electrodes in some embodiments, and the silicondoped with oxygen may be directly against the electrodes in otherembodiments. In some embodiments, the silicon doped with oxygen maycomprise oxygen to a concentration within a range of from greater thanzero atomic percent to less than or equal to about 10 atomic percent.

The embodiments of FIGS. 8B and 8C show that in some embodiments one ofmaterials 40 and 42 may consist of, or consist essentially of silicon;while the other comprises silicon doped with germanium. The silicon maybe directly against the electrodes in some embodiments, and the silicondoped with germanium may be directly against the electrodes in otherembodiments. In some embodiments, the silicon doped with germanium maycomprise germanium to a concentration within a range of from greaterthan or equal to about one atomic percent to less than or equal to about50 atomic percent.

The embodiments of FIGS. 9B and 9C show that in some embodiments one ofmaterials 40 and 42 may consist of, or consist essentially of silicon;while the other comprises silicon doped with carbon. The silicon may bedirectly against the electrodes in some embodiments, and the silicondoped with carbon may be directly against the electrodes in otherembodiments. In some embodiments, the silicon doped with carbon maycomprise carbon to a concentration within a range of from greater thanor equal to about one atomic percent to less than or equal to about 50atomic percent.

The embodiments of FIGS. 10B and 10C show that in some embodiments oneof materials 40 and 42 may comprise silicon (which may or may not bedoped with one or more of nitrogen, oxygen, germanium and carbon); whilethe other comprises oxide (which may comprises one or more oxidesselected from the group consisting of hafnium oxide, zirconium oxide,strontium oxide, titanium oxide and lanthanum oxide). The silicon may bedirectly against the electrodes in some embodiments, and the oxide maybe directly against the electrodes in other embodiments.

The selector materials 40 and 42 of FIG. 4 are shown to comprisethicknesses T₁ and T₂; which in some embodiments may be within a rangeof from about 3 Å to about 350 Å. In some embodiments, materialscorresponding to the oxides of FIGS. 10B and 10C may have thicknesses offrom about 3 Å to about 20 Å, while other materials of FIGS. 6-9 mayhave thicknesses of from about 20 Å to about 350 Å. Although bothsections of material 40 are shown having the same thickness as oneanother, in other embodiments one of the sections may have a differentthickness than the other. Further, although material 42 is shown havinga different thickness than material 40, in other embodiments material 42may have about the same thickness as material 40.

The embodiment of FIG. 4 may be considered to be an example of aconstruction in which a selector region comprises a stack of first andsecond materials arranged in the configuration first material/secondmaterial/first material. In contrast, FIG. 5 illustrates a switchingcomponent 22 b having selector region 34 b having a larger stackcomprising first material/second material/first material/secondmaterial/first material. In other embodiments, other stacks besidesthose shown in FIGS. 4 and 5 may be utilized.

The materials 40 and 42 of FIG. 5 may be the same as those describedabove with reference to FIG. 4; and FIGS. 6D, 6E, 7D, 7E, 8D, 8E, 9D,9E, 10D and 10E illustrate some example configurations for the selectorregion 34 b of FIG. 5 relative to example switching components 22 b.

In some embodiments, switching components may be formed to comprisemultiple constructions of the types described above in FIGS. 3-10, withthe constructions being stacked one atop another. For instance, FIGS.11A and B illustrate example switching components 22 c and 22 d havingelectrodes 50-52 and 60-63; and comprising semiconductor material 34between the electrodes. In the illustrated configuration, thesemiconductor material comprises silicon doped with one or more ofnitrogen, oxygen, germanium and carbon. Although the same semiconductormaterial 34 is shown utilized throughout the constructions, in otherembodiments different semiconductor materials may be utilized. Theelectrodes 50-52 and 60-63 may comprise any of the compositionsdescribed above relative to electrodes 30 and 32 of FIG. 3.

The electronic devices discussed above may be incorporated intoelectronic systems. Such electronic systems may be used in, for example,memory modules, device drivers, power modules, communication modems,processor modules, and application-specific modules, and may includemultilayer, multichip modules. The electronic systems may be any of abroad range of systems, such as, for example, clocks, televisions, cellphones, personal computers, automobiles, industrial control systems,aircraft, etc.

Unless specified otherwise, the various materials, substances,compositions, etc. described herein may be formed with any suitablemethodologies, either now known or yet to be developed, including, forexample, atomic layer deposition (ALD), chemical vapor deposition (CVD),physical vapor deposition (PVD), etc.

The particular orientation of the various embodiments in the drawings isfor illustrative purposes only, and the embodiments may be rotatedrelative to the shown orientations in some applications. The descriptionprovided herein, and the claims that follow, pertain to any structuresthat have the described relationships between various features,regardless of whether the structures are in the particular orientationof the drawings, or are rotated relative to such orientation.

The cross-sectional views of the accompanying illustrations only showfeatures within the planes of the cross-sections, and do not showmaterials behind the planes of the cross-sections in order to simplifythe drawings.

When a structure is referred to above as being “on” or “against” anotherstructure, it can be directly on the other structure or interveningstructures may also be present. In contrast, when a structure isreferred to as being “directly on” or “directly against” anotherstructure, there are no intervening structures present. When a structureis referred to as being “connected” or “coupled” to another structure,it can be directly connected or coupled to the other structure, orintervening structures may be present. In contrast, when a structure isreferred to as being “directly connected” or “directly coupled” toanother structure, there are no intervening structures present.

Some embodiments include a switching component comprising a selectorregion between a pair of electrodes. The selector region comprisessilicon doped with one or more of nitrogen, oxygen, germanium andcarbon.

Some embodiments include a switching component comprising a firstelectrode, a selector region over the first electrode, and a secondelectrode over the selector region. The selector region comprises astack of alternating first and second materials, with at least one ofthe first and second materials comprising semiconductor.

Some embodiments include a memory unit comprising a memory cell and aselect device electrically coupled to the memory cell. The select devicecomprises a selector region between a pair of electrodes. The selectorregion comprises semiconductor doped with one or more of nitrogen,oxygen, germanium and carbon; and the select device has current versusvoltage characteristics which include snap-back voltage behavior.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

I claim:
 1. A switching component, comprising: a selector region betweena pair of electrodes; wherein the selector region comprises silicondoped with nitrogen; and wherein the dopant comprises nitrogen to atotal concentration within a range of from greater than 0 atomic percentto about 10 atomic percent.
 2. The switching component of claim 1wherein the electrodes are a same composition as one another.
 3. Theswitching component of claim 1 wherein the electrodes are differentcompositions relative to one another.
 4. The switching component ofclaim 1 wherein at least one of the electrodes comprises one or more ofTa, Ti and W, in combination with nitrogen.
 5. The switching componentof claim 1 wherein said at least one of the electrodes further comprisesone or more of O, C and Al.
 6. The switching component of claim 1wherein both of the electrodes comprise carbon.
 7. The switchingcomponent of claim 1 wherein at least one of the electrodes consists ofcarbon and nitrogen.
 8. The switching component of claim 1 wherein theselector region is a single homogenous material that directly contactseach electrode of said pair of electrodes.
 9. The switching component ofclaim 1 wherein both electrodes of said pair consist of carbon.
 10. Theswitching component of claim 1 wherein the selector region comprises twoor more different materials.
 11. A switching component, comprising: afirst electrode; a selector region over the first electrode; a secondelectrode over the selector region; wherein the selector regioncomprises a stack of alternating first and second materials, with one ofthe first and second materials comprising semiconductor and the other ofthe first and second materials comprising nitrogen-doped semiconductor;and wherein said other of the first and second materials comprisessilicon doped with nitrogen to a concentration within a range of fromgreater than 0 atomic percent to about 10 atomic percent; and whereinsaid one of the first and second materials consists of silicon.
 12. Theswitching component of claim 11 wherein the selector region comprisesthe nitrogen-doped silicon directly against each of the electrodes. 13.The switching component of claim 11 wherein the selector regioncomprises the material consisting of silicon directly against each ofthe electrodes.
 14. The switching component of claim 11 wherein thestack comprises first material/second material/first material.
 15. Theswitching component of claim 11 wherein the stack comprises firstmaterial/second material/first material/second material/first material.16. A memory unit, comprising: a memory cell; a select deviceelectrically coupled to the memory cell; the select device comprising aselector region between a pair of electrodes, wherein the selectorregion comprises semiconductor doped with nitrogen and has currentversus voltage characteristics which include snap-back voltage behavior;wherein the selector region is a single homogenous material thatdirectly contacts each electrode of said pair of electrodes; and whereinthe single homogenous material comprises silicon doped with nitrogen toa concentration within a range of from greater than 0 atomic percent toabout 10 atomic percent.
 17. The memory unit of claim 16 wherein bothelectrodes of said pair consist of carbon.